# Connecting ProFix: which T-slot nuts and connectors fit? Quelle: > The slot, the thread, assembly access and operating conditions decide which connection suits your profile. Profiles The slot, the thread, assembly access and operating conditions decide which connection suits your profile. This is how you narrow down the choice and avoid typical mistakes before ordering. MVG editorial team · Values from our production and the material standards Published on 11 September 2026 · 4 min read Example of a T-slot nut design. Take dimensions and threads from the respective item. ## Start with the profile Note the profile series and the slot size. The outside dimensions alone are not enough: a connector must fit the slot and the intended assembly. Use the data of the specific profile and accessory item; systems that look similar are not automatically compatible. In the ProFix range, the 20 × 20 MINI profile typically has slot 5, and most profiles from 30 × 30 have slot 8. There are also individual designs with slot 6 or slot 10. The information on the respective profile page is decisive. There you will also find the dimensional drawing with the core bore. If you are still choosing the profile, check the load capacity first. With the deflection calculator you can estimate which cross-section suits the length and load. Then choose the connection. ## Typical types of connection at a glance Angle connectors: an angle bracket sits on the outside of two profiles and is fixed in the slots with T-slot nuts and screws. It is suitable for frames, racks and right-angled joints. According to the item data, the angle brackets in the range need no profile machining, and the position remains adjustable along the slot. Clamp connectors: a clamp connector sits in the end of the profile and tightens via a T-slot nut in the slot of the cross profile. The connection is hardly visible from the outside and, depending on the design, can be readjusted. Whether and which machining is needed at the profile end is stated on the respective item; if nothing is given, please ask before ordering. Bolt and butt connectors: these connectors join profiles at the end face, for example via a connector bolt or a screw in the core bore. They are used when the connection should be inside and the outer contour should stay smooth. Typically this requires machining of the profile, such as a hole for assembly access or a thread. Slide-in T-slot nuts: they are pushed into the slot via an open profile end. In the ProFix range these are typically the heavy designs and the T-slot nut bar. Their advantage is the wide seat in the slot; however, they must be inserted before the frame is closed. Swivel-in T-slot nuts: they are inserted into the slot from the front and turned into position. This allows installation later, even when the profile ends are already built in. Hammer nuts and many T-slot nuts with a web in the range are designed this way. ## Slide in or insert later Slide-in T-slot nuts are inserted via an accessible profile end. Depending on the design, swivel-in versions can be inserted into the slot later. Before assembly, check whether the profile ends will still be accessible afterwards. With slide-in T-slot nuts, plan a few spare nuts in the slots if add-on parts may follow later. Depending on the item, T-slot nuts have a spring ball or a guide web. The spring ball holds the nut in position, even in vertical slots. The web guides the nut in the slot. Both make assembly easier; the details are given for each item under “T-slot nuts and screws”. ## Choose thread and screw length together M4, M5, M6 or M8 denote the metric thread. T-slot nut and screw must match. The screw length also depends on the thickness of the part being fixed and the available thread engagement. A screw that is too long must not touch the bottom of the slot. As a rule: the screw must engage the thread of the T-slot nut sufficiently, but must not bottom out in the nut or in the profile. If the screw bottoms out first, it does not clamp the part, even though it can no longer be turned. So calculate: thickness of the add-on part plus engagement length in the T-slot nut, and compare the result with the space to the bottom of the slot according to the dimensional drawing. For T-slot nuts with two threads (for example 2 × M6 or 2 × M8), this applies to each screw. ## Consider the whole connection Angle brackets, connectors, screws and T-slot nuts together form one connection. For sets, check the stated scope of delivery. Load capacity and tightening torque depend on the item and the design; a general size selection does not replace verification for the finished frame. The scope of delivery differs from item to item. An angle bracket set typically contains the bracket, cover cap, T-slot nuts and screws; the 80 × 80 set has more T-slot nuts and screws than the 40 × 40 set. Clamp connector sets are available with a swivel-in or with a heavy T-slot nut. According to the item data, bolt butt connector sets contain no T-slot nut. So count for each joint what the set contains and what you need to order in addition. ## Which solution when? The decision depends less on the profile than on assembly, load and appearance. - Installation later required: swivel-in T-slot nuts or hammer nuts. - No profile machining wanted: angle connectors with T-slot nuts. - Smooth outer contour, connection not visible: clamp, bolt or butt connectors; clarify machining in advance. - High load or vibration: do not choose by thread size alone. Check larger or longer T-slot nuts and several fixing points, verify the whole structure and check screwed joints after commissioning. ## Common mistakes These mistakes usually only show up during assembly – and can be avoided before ordering. - Screw too long: it touches the bottom of the slot and does not clamp. - Wrong slot size: a T-slot nut for slot 8 does not fit slot 5 or slot 6, and the other way round it does not sit securely. - No assembly access: slide-in T-slot nuts were forgotten and the profile ends are already closed. Or there is no tool access for a screw in the core bore. - Scope of delivery not checked: not every set is complete. A bolt butt connector set, for example, contains no T-slot nut – it must be ordered separately. ## At a glance - Profile series and slot size known - Assembly access to the profile ends checked - Installation later required? Then plan swivel-in T-slot nuts - Profile machining possible or wanted? Otherwise choose angle connectors - High load or vibration? Verify the connection and frame separately - Appearance important? Provide internal connectors or cover caps - Thread and screw length matched; screw does not touch the bottom of the slot - Scope of delivery and required quantities compared [Choose the right ProFix system →](https://mvg-frankfurt.de/en/aluminium-profiles) ## Matching products [ProFix **Connectors and angles** Angle, clamp and bolt connector sets. *View accessories →*](https://mvg-frankfurt.de/en/aluminium-profiles/nut-8/zubehoer/verbinden) · [ProFix **T-nuts and screws** Slide-in, swivel-in, with web or spring ball. *View accessories →*](https://mvg-frankfurt.de/en/aluminium-profiles/nut-8/zubehoer/nutensteine-schrauben) · [ProFix **Covering and sealing** End caps and cover profiles. *View accessories →*](https://mvg-frankfurt.de/en/aluminium-profiles/nut-8/zubehoer/abdecken-dichten) · [Profile **Profile 20 × 20 slot 5 MINI** Dimensional drawing with centre bore. *View the profile →*](https://mvg-frankfurt.de/en/aluminium-profiles/nut-5/aluprofil-20x20-mini) · [Profile **Profile 40 × 40 slot 8 light** Dimensional drawing, statics, instant price. *View the profile →*](https://mvg-frankfurt.de/en/aluminium-profiles/nut-8/aluprofil-40x40-leicht) · [Calculators **Calculate deflection** Which profile carries the load? Free in the browser. *Go to the calculator →*](https://mvg-frankfurt.de/en/calculators/profile-deflection) ## Questions about your part? Our sales team advises you on material, manufacturing and delivery time. [Call: (069) 94 21 30 - 0](tel:+496994213000) · [Email info@mvg-frankfurt.de](mailto:info@mvg-frankfurt.de?subject=Question%20about%3A%20Connecting%20ProFix%3A%20which%20T-slot%20nuts%20and%20connectors%20fit%3F) ## Related articles - [Design & manufacturing Design furniture with Claude Code and have it made in our digital factory With AI, an idea becomes a finished construction plan with a bill of materials. 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